Atomic structure

• Atoms are electrically neutral as the number of protons equals the number of electrons
• Sub-atomic particles in an ion:

  • An ion is formed when an electrically neutral atom loses or gains electrons
  • Charged particles (ions) are formed
  • Number of protons is not equal to the number of electrons
  • Elements that add electrons keep their name, while those that lose electrons change their name
• Electronic structure:

  • Arrangement of electrons in an atom is represented using electronic configuration / electronic structure
  • Each shell holds a certain maximum number of electrons
  • Valence shell holds electrons farthest from the nucleus and are called valence electrons
• The number of protons is equal to the atomic number.
• The number of neutrons = Nucleon number - Proton Number
• • (A/Z) | X
  • Atomic mass [A] , is the nucleon number of an atom
  • Atomic number [Z] , number of protons in an atom
  • Atomic Symbol [X] , the element
• Mass number, is the total number of protons and neutrons in an atom
• Isotopes, have different numbers of neutrons but same number of protons